- Concomitant use of rifampin, ergot derivatives (i.e. dihydroergotamine, ergotamine), cisapride, lovastatin, simvastatin, triazolam, orally administered midazolam, carbamazepine, phenytoin, St. John's wort, ketoconazole, itraconazole, clarithromycin, telithromycin, amiodarone, bepridil, flecainide, propafenone, quinidine, voriconazole or nefazodone.